Synthetic lubricants



Patented Mar. 14, 1950 UNITED STATES PATENT OFFICE SYNTHETIC LUBRICANTSNo Drawing.

Claims.

This invention has to do with a new and novel class of syntheticlubricants and with a method of preparing the same. More particularly,the invention relates to synthetic lubricants obtained by polymerizationof normal, alpha mono-olefins in the presence of phosphorus sulfides.

As is well known to those familiar with the art, olefins have previouslybeen polymerized and condensed, thermally or catalytically, to formproducts of varying character. Olefins have also been reacted atelevated temperatures with phosphorus sulfides, and with elementalphosphorus and sulfur, to form phosphorusand/ or sulfur-containingproducts. The latter products have been developed, for example, for useas additives for lubricating oils and the like. In the prior art, it hasbeen indicated that olefins as a class may be so reacted to producelubricating oil addition agents. There has been little emphasis upon thecharacter of the olefins, although relatively shortchain iso-olefins,such as isobutyiene, and polymers thereof, have received considerableattention. Long chain olefins, such as cetene (C16) and melene (C30)have also been mentioned, no distinction being made as to the positionof the double bond. With regard to the phosphorus sulfide, andphosphorus and sulfur reactants, it has been disclosed that at least oneper cent by weight of phosphorus sulfide, or corresponding quantity ofphosphorus and sulfur, is necessary in order to form an effectiveaddition agent. Temperatures necessary for reaction have been within therange of 200 F. to 500 F.

While the foregoing phosphorusand sulfurcontaining products have beeneffective in stabilizing lubricating oils when incorporated therein inminor proportions, as of the order of 0.5 to 10 per cent, such productshave not been suitable for use as lubricants per se. They are generallyrather acidic, as indicated by neutralization number determinations (N.N.), and some have poor viscosity and/ or pour characteristics.

In contrast to prior art developments, it has now been discovered thatsynthetic lubricants of excellent character, particularly high viscosityApplication October 29, 1948, Serial No. 57,421

index, low pour point and great stability, are formed by polymerizingcertain normal, alpha mono-olefins in the presence of phosphorussulfides, or elemental phosphorus and sulfur, under the critical andinter-related reaction conditions hereinafter described.

REACTANTS As indicated above, the mono-olefin reactants of thisinvention are normal or straight chain alpha mono-olefins and containfrom 5 to 18 carbon atoms. Such mono-olefins are normally liquid attemperatures of the order of 20-25 C. Illustrative of such mono-olefinsare the following: pentene-l, octene-l, decene-l, dodecene-l,octadecene-l, and the like. Preferred however, of such olefins are thosehaving from 8 to 12 carbon atoms, with decene-l representing aparticularly desirable olefin. It will be clear from the foregoingexamples that an alpha olefin may also be referred to as a l-olefin.

Not only may the mono-olefins of the aforesaid character be usedindividually in this invention, but they may also be used in admixturewith each other. In addition, olefin mixtures contalning a substantialproportion of such monoolefins may be used. Preferred of such mixturesare those containing a major proportion of a l-olefin or of l-olefins.mixtures are those obtained by the cracking of paraffin waxes and otherparaflin products; those obtained from the Fischer-Tropsch and relatedprocesses.

These hydrocarbon mixtures may contain, in

; addition to the l-olefin or l-olefins, such materials as: otherolefins, paraflins, naphthenes and aromatics.

In many instances, in commercial operation, it will be found desirableto use technical grades of l-olefins. Mixed olefinic materials derivedfrom thermal cracking of hydrocarbon wax or from the Fischer-Tropschprocess constitute satisfactory charging stocks. In this connection, itmust be noted that it is suspected that substantially straight chainl-oleflns, that is, l-olefins Representative of such in which the lengthof the side chain (or chains) is short relative to the length of themain chain, and in which the side chain (or chains) is not adjacent tothe terminal .double bond, are also suitable, although less advantageouscharge stocks for the purpose of the present invention. In view of theunavailability of such olefins, however, no test data can be adduced toconfirm this suspicion.

That the character of the olefin reactant is critical is shown byseveral illustrative examples hereinbelow. For example, when a normalolefin having from 5 to 18 carbon atoms and having an interior doublebond rather than a terminal double bond, is used, the product isobtained in low yield and is characterized in most instances by a lowviscosity index and/or high corrosivity toward copper. Similar resultsare obtained with branched chain olefins having an interior double bond,and with branched chain l-oleflns in which a side chain is adjacent tothe terminal double bond.

The phosphorus and sulfur reactant may be in the proportions ofreactants is demonstrated by the form of elemental phosphorus andelemental synthetic oils is PzSs which represents the preferredreactant. When elemental phosphorus and elemental sulfur are used underthe conditions of operation described below, it is most probable that aphosphorus sulfide or phosphorus sulfides are formed in situ. It will beunderstood that elemental phosphorus and/ or elemental sulfur may beused with one or more of the phosphorus sulfides in the preparation of asynthetic oil.

REACTION CONDITIONS The most critical reaction conditions, coupled withthe specific character of-the aforesaid reactants, are the proportionsof the reactants and the reaction temperature.

It has been found that the proportion of phosphorus sulfide reacted withthe l-olefin reactant is critical and should be maintained below one percent, by weight, of their combined weight. The proportion of phosphorussulfide used falls within the range of from about 0.01 per cent to lessthan one per cent by weight of the olefinphosphorus sulfide charge. Whenelemental phosphorus and sulfur are used in place of a phosphorussulfide, the proportion of phosphorus will be of the order of 0.003 to0.9 per cent by weight of the charge, and the proportion of sulfur willbe from about 0.007 to 0.9 per cent of said charge, the total proportionof phosphorus and sulfur not exceeding 1 per cent. Correspondingly, whena small quantity of elemental phosphorus, preferably red phosphorus, isused with a phosphorus sulfide, the combined quantity of phosphorus andphosphorus sulfide will be less than one per cent by weight of thecharge. A similar precaution is observed when elemental sulfur, or whenboth elemental sulfur and elemental phosphorus, are used with aphosphorus sulfide.

Specifically in regard to the proportions of reactants, it has beennoted that when more than one per cent of a phosphorus sulfide, as P285,is used, a product of relatively low viscosity index is obtained in lowyield. The influence of several illustrative examples shown hereinbelow.

With regard to reaction temperature, it has been found that thetemperature should be above 600 F. and below 750 F. When temperaturesbelow 600 F. are used, the yield of product is generally low, and theproduct is characterized by a relatively high degree of corrosivity tocopper and other metals as indicated by neutralization numberdeterminations. When temperatures of 750 F. and greater are used, theyield is again low, and the product is of low viscosity index and haspoor color. Most advantageous results are obtained with reactiontemperatures between about 640 F. and about 700 F.

Other reaction conditions to be considered in forming the lubricantscontemplated herein are pressure and reaction time. The pressure to beused is not particularly critical. It may range from about 100 to about4000 pounds per square inch, or even higher.

Reaction time varies inversely with temperature. Satisfactory productsand satisfactory yields of the same may be obtained with reaction timesas short as one hour or less and as long as twenty hours. With highertemperatures, as those approaching the upper limit of 750 F., shorterreaction periods are used; correspondingly, with lower temperatures, asthose of the order of 625 F., longer reaction periods are used.Preferably, the time is in the neighborhood of 10 hours at 625-650 F.,and about 3 hours at 700-725 F.

EXAMPLES In order to illustrate the principles of this invention, theresults of a series of typical, and non-limiting, condensations are setforth in tabular form in Table I below. These condensations were carriedout in rocking-type bombs (American Instrument Co.). The reactants werecharged to the bombs, which were then heated to the desired temperaturefor the desired length of time. Thereafter, the bombs were cooled, anddischarged. The contents of the bombs were vacuum topped to removeunreacted hydrocarbon materials. It should be noted that the reactiontimes, recited as Time, hours in Table I, represent the time intervalsduring which the bombs were maintained at the desired temperature, anddo not include the time intervals' necessary to heat the bombs and-theircontents to the desired temperature, and do not include the timeintervals necessary to cool the bombs after heat to the bombs has beendiscontinued. In general, about 2 hours are required to raise thetemperature from 60-08 F. to 640 F., and about 10 hours to coolthereafter to 60-80 F., in runs such as shown in Table I. I

The condensation products discharged from the bombs, or other reactionvessels, were vacuum topped and filtered, as in the runs shown in TableI. To distinguish the condensation products from the distillatefractions thereof,

the refined oils are identified as residual oils. The latter termidentifies the oils from which unreacted materials and products ofintermediate boiling range have been separated.

All'of the tests and analyses to which the residual oils in Table I weresubjected are well known standard tests. In this connection, it will benoted that the designation N. N. refers to the neutralization number,which is a measure of the acidity of the oil.

TABLE I Run No 1 3 4 5 6 Olefin Octene-l..-- 0ctene-2. 2-Ethyl Hexene-l.Decene-1...- Decene-1 Decene l.

Pirts by eight 33 336 330 28 280 700.

Mo] 1r Proportrom. 5.0. Phosphorus Sulfide. P185.

Parts by Weight 2.

Per cent by Weig 0.3.

Molar Proportion Phosphorous...

Parts by Wei Per Cent by Wei Molar Proportion Sulfur...

ight... Weight. Molar Proportion Temperature, F Time, Hrs Max. Pressure,p. s. i. g Residual Oil:

Parts by Weight Yield, Per Cent Viscosity 100 F., Viscosity 210 F., CsV. I Pour Point, "F Specific Gravity. N. N Color (Lovibond)..

Olefin Max. Pressure, p. s. i. g

Oil:

Residual Parts by Weight Yield, Per Cent Viscosity 100 F., Cs. Viscosity210 F., Cs. V. I Pour Point, F. Specific Gravity Phosphorus Per CentSulfur 1 Ramsbottom carbon Residue 0.02. Ramsbottom carbon Residue 0.07.

cates that a synthetic oil of excellent quality may 55 be prepared byreacting octane-1 with PzSs under the conditions described above,namely, 650 F. and less than one per cent by weight of P2S5. Thelubricant obtained in run 1 is obtained in a yield of 48.5 per cent; ithas a V. I. of 104.7, a pour point of less than 30 R, an N. N. of only0.1, and a Lovibond color of only 4. In contrast, run 2 shows an oilproduct obtained by reacting octane-2, which is not a normal, alphamonoolefin, with P235 under substantially the same conditions. The yieldin run 2 is only 3.0 per cent and the product has considerable acidity,as indicated by an N. N. of 5.5. Also in contrast with run 1 is run 3,wherein 2-ethyl hexene-l is used. Here again, the olefin is not anormal, alpha mono-olefin. In run 3, the yield is again low, onl 5.3 percent, and the V. I. is but 26.5.

Runs 4 through 9 show oil products obtained temperature is only 505 F.,below the prescribed minimum temperature,and the quantity of P285 is 2.1per cent by weight, greater than the prescribed maximum quantity. Withsuch condi tions in run 4, the oil product is obtained in relatively lowyield, 9.0 per cent, and has a high degree of acidity, as shown by an N.N. of 23.5.

0 Run 5 was also carried out with a low temperature, only 600 F., withthe result that the product was obtained in very low yield, 3.6 percent. In comparison with runs 4 and 5, run 6 shows reaction conditionswithin the prescribed limits: 640 F. and 0.3 per cent by weight of P285.The yield of product in run 6 was 18.9 per cent, with the productcharacterized by the following desirable properties: V. 1., 101.5; pourpoint, less than 30 F.; N. N., 2.4; Lovibond color, 54.

Run 7 also illustrates the invention, showing an oil obtained at 700 F.The oil product, in comparison with the desirable oil product of run 6,has a slightly lower V. I., but a much lower from decene-l and P235. Inrun 4, the reaction 75 degree of acidity (N. N.=0.3) and better color.

Run 8 demonstrates again the effect of an excessive quantity of P285. Incontrast with run 7, the oil product of run 8 is obtained in loweryield, only 11.5 per cent; has a substantially lower V. I., only 83.7;and is of excessively dark color, 110. Run 9 reveals the effect of hightemperature at the upper limit of the range described above. At 750 F.,the yield is low, 9.6 per cent; the viscosity index is but 57.2; and thecolor is again very dark, 500.

Runs 10 and 11 demonstrate the production of oil products fromphosphorus and sulfur, rather than a phosphorus sulfide. Under theconditions of reaction, however, it is probable that a phosphorussulfide or more than one such sulfide is formed. Run 10 is illustrativeof the invention, with an excellent oil product being formed therein.Run 11, however, is conducted with an excessive quantity of phosphorusand sulfur, the sum being greater than one percent. Contrasting runs 10and 11, it will be noted that the yield of run 10 is 49.8 per cent andthat of run 11 only 13.4 per cent. The V. I. of the oil product of run10 is 119.6, substantially greater than that of run 11, namely, 87.3.Further, the acidity of the oil of run 10 is negligible, only 0.1 N. N.;whereas, the oil of run 11 has an N. N. of 21.7. The great differencebetween the two oils is also revealed by color determinations, 2.3 forthe oil of run 10 compared with 575 for the oil of run 11.

Referring further to the results provided in 'Table I, it will be notedthat the oils of runs 1,

6, 'l and 10, all of which illustrate the invention, have kinematicviscosities, at 210 F., of the order of 2.12-2.57 centistokes. below SAE10 oils in viscosity and are excellently suited for use as break-inoils, blending stocks, cold climate lubricants and the like.Furthermore, the properties of the synthetic oils are such as to meetthe requirements for turbo-jet lubricating oils. The latter oils, forexample, should have low viscosity, low pour point and high viscosityindex.

As a further note, on Table I, the molecular weight of th oil of run 6was found to be 331 using cyclohexane as a solvent, and 313 usingbenzene as a solvent. This would indicate that the oil is predominantlycomprised of dimers (molecular weight 280) and trimers (molecular weight420) of decene-l.

A number of well-known tests were made on the residual oils shown inTable I, above, to determine their characteristics and usefulness. Forexample, the residual oil from run 6 was subjected to the copper striptest, which is a standard test for lubricants. The purpose of the copperstrip test is to detect free sulfur and corrosive sulfur, the latteroften being present as Such oils, thereof, are

mls. of the oil to be tested are placed in a mls. beaker along with apolished copper strip, about /z inch by 2 inches. The copper strip isbent into a V and so placed in the beaker that the flat surface thereofdoes not touch the bottom or sides of the beaker. The oil sample in thebeaker completely covers the copper strip. The beaker, containing oilsample and copper strip. is placed in an electric oven for the requiredperiod of time. Thereafter, the beaker is removed from the oven and thecopper strip is removed from the beaker. The strip is washed withpetroleum ether and then is examined for corrosion. After 24 hours at100 C., the copper strip subjected to the residual oil from run 6 wasonly slightly stained, the color being desisnated brassy." The oilsample was light and and there was no sludge therein. This result iscomparable to that normally realized with an SAE-lil solvent refinedPennsylvania motor oil subjected to the same test. This test, then,demonstrates that the sulfur present in the oil is firmly bound and thatno free sulfur is present in the oil.

In sharp contrast to the oil of run 6 in the copper strip test, the oilof run 4 fails badly in this test. With only 0.5 per cent of the oil ofrun 4 blended with the aforesaid SAE-lO motor oil, under the sameconditions, the copper strip was black, and the oil blend was dark incolor and contained some sludge. Such results clearly indicate that theoil of run 4 is highly corrosive and unstable. It will be noted that theoil of run 4 has an N. N. of 23.5, whereas the oil of run 6 has an N. N.of only 2.4: further, the oil of run 4 contains 12.16 per cent sulfur,as compared with only 0.38 per cent for the oil of run 6.

The stability of the oils of this invention is revealed by the resultsof a catalytic oxidation test, to which were subjected several of theresidual oils shown in Table 1, above. In this test 6.5 feet of No. 14(Brown and Sharpe gauge) iron wire (15.6 square inch), 6.2 inches of No.18 (B. and S.) copper wire (0.78 square inch), 3.33 inches of No. 12 (B.and S.) aluminum wire (0.87 square inch), a inch square of inch leadsheet square inch), and 25 cc. of the test oil were placed in a glasstest tube, heated to 260 1". and air blown therethrough at the rate of10 liters per hour for 40 hours.

Changes in the characteristics of the oil, sludge formed, and effects ofoil on the copper coil and on the lead sheet were reported. On the basisof these changes, the residual oils were rated as compared with a SAE-IOsolvent refined Pennsylvania motor oil subject to the same test. Theresults of these tests and of the comparisons with SAE-lO Pennsylvaniaoil are reported in Table II loosely-bound" sulfur in an oil. In thistest, 50 below.

TABLE II Catalytic oxidation test Run No. igg- Analyses of Oil:

KI VIE 56 cs3: '1

Per Cent Vis. Increase.

Very Poor From inspection of the results shown above in Table II, itwill be seen that the new synthetic oils are equal to or better thansAE-lO Pennsylvania solvent refined motor oil in every respect.

As will be evident from the data presented above in Tables I and II, thecondensation products of this invention are highly desirable lubricantsper se. They are also of considerable value as blending agents for otherlubricating oils. In view of the inherent stability of the syntheticoils, they impart stability to the oils with which they are blended. Soalso, they impart desirable viscosity index (V. I.) and poor pointcharacteristics to the oils in combination therewith, for, as indicatedabove, they have advantageous viscosity index and pour point properties.In short, the synthetic oils find utility in upgrading" otherlubricants. Typical oils with which the synthetic oils may be blendedare mineral oils such as are normally used in internal combustion andturbine engines. when so blended, the synthetic oils may comprise themajor proportion of the final blended oil, or may even comprise a minorproportion thereof.

One or more of the individual properties of the synthetic lubricants ofthis invention may be further improved by incorporating therewith asmall, but effective amount, of an addition agent such as a detergent,an extreme pressure agent, a foam suppressor, a viscosity index (V. I.)improver, etc. Typical detergents which may be so used are metal saltsof alkyl-substituted aromatic sulfonic or carboxylic acids, asillustrated by diwax benzene barium sulfonate and barium phenate, bariumcarboxylate of a wax-substituted phenol carboxylic acid. Extremepressure agents are well known; illustrating such materials are numerouschlorine and/or sulfur containing compositions, one such material beinga chlor-naphtha xanthate. Silicones, such as dimethyl silicone, may beused to illustrate foam suppressing compositions. Viscosity indeximproving agents which may be used are typified by polypropylenes,polyisobutylenes, polyacrylate esters, and the like.

contemplated also as within the scope of this invention is a method oflubricating relatively moving surfaces by maintaining therebetween afilm consisting of any of the aforesaid oils.

It is to be understood that the foregoing descriotion and representativeexamples are nonlimiting and serve to illustrate the invention, which isto be broadly construed in the light of the language of the appendedclaims.

I claim:

1. The method of preparation 'of a viscous oil, which comprises:polymerizing, at a temperature above 600 F. and below 750 F., a normal,alpha mono-olefin having from to 18 carbon atoms with a materialselected from the group consisting of a phosphorus sulfide, elementalphosphorus with elemental sulfur, and mixtures thereof, the

8. The method of preparation of a viscous oil, which comprises:polymer-wing, at a temperature above 600 F. and below 750 F., a normal,alphamono-olefin having from 8 to 12 carbon atoms with a materialselected from the group consisting of a phosphorus sulfide, elementalphosphorus with elemental sulfur, and mixtures thereof, the

' quantity of said material being less than one per quantity of saidmaterial being less than one per cent by weight of the combined weightof said olefin and said material.

2. The method of preparation of a viscous oil, which comprises:polymerizing, at a temperature between about 640 F. and about 700 F., anormal, alpha mono-olefin having from 5 to 18 carbon atoms with amaterial selected from the group consisting of a phosphorus sulfide,elemental phosphorus with elemental sulfur, and mixtures thereof, thequantity of said material being 'less than one per cent by weight of thecombined weight of said olefin and said material.

cent by weight of the combined weight of said oleflns and said material.

4. The method of preparation of a viscous oil, which comprises:polymerizing, at a temperature above 600 F. and below 750 F., a normal,alpha mono-olefin having from 5 to 18 carbon atoms with a materialselected from the group consisting of a phosphorus sulfide, elementalphosphorus with elemental sulfur, and mixtures thereof, the quantity ofsaid material being greater than about 0.01 per cent and less than oneper cent by weight of the combined weight of said olefin and saidmaterial.

5. The method of preparation of a viscous oil, which comprises:polymerizing, at a temperature above 600 F. and below 750 F., a normal,alpha mono-olefin having from 5 to 18 carbon atoms with a phosphorussulfide, the quantity of said sulfide being greater than about 0.01 percent and less than one per cent of the combined weight of said olefinand said sulfide.

6. The method of preparation of a viscous oil, which comprises:polymerizing, at a temperature above 600 F. and below 750 a normal,alpha mono-olefin having from 5 to 18 carbon atoms with a mixture ofelemental phosphorus and elemental sulfur, the quant ty of saidphosphorus and sulfur being greater than about 0.01 per cent and lessthan one per cent by weight of the combined weight of said olefin andsaid mixture.

7. A viscous oil obtained by: polymerizing, at a temperature above 600.F. and below 750 F., a normal, alpha mono-olefin having from 5 to 18carbon atoms with a material selected from the group consisting of aphosphorus sulfide, elemental phosphorus with elemental sulfur, andmixtures thereof, the quantity of said material being less than one percent by weight of the combined weight of said olefin and said material.

8. A viscous oil obtained by: polymerizing, at a temperature betweenabout 640 F. and about 700 F., a normal, alpha mono-olefin having from 5to 18 carbon atoms with a material selected from the group consisting ofa phosphorus sulfide, elemental phosphorus with elemental sulfur, andmixtures thereof, the quantity of said material being less than one percent by weight of the combined weight of said olefin and said material.

9. A viscous oil obtained by: polymerizing, at a temperature above 600F. and below 750 F., a

normal, alpha mono-olefin having from 8 to 12 carbon atoms with amaterial selected from the group consisting of a phosphorus sulfide,elemental phosphorus with elemental sulfur, and mixtures thereof, thequantity of said material being less than one per cent by weight of thecombined weight of said olefin and said material.

10. A viscous oil obtained by: polymerizing, at a temperature above 600F. and below 750 F., a normal, alpha mono-olefin having from 5 to 18carbon atoms with a material selected from the group consisting of aphosphorus sulfide, elemental phosphorus with elemental sulfur, andmixtures thereof, the quantity of said material being greater than about0.01 per cent and less than asoouee 11 one per cent by weight or thecombined weight of said olefin and said material.

11. A viscous oil obtained by: polymerizing, at a temperature above 6001". and below 750 1"., a normal, alpha mono-olefin having from 5 to 18carbon atoms with a phosphorus sulfide, the quantity of said sulfidebeing greater than about 0.01 per cent and less than one per cent of thecombined weight of said olefin and said sulfide.

12. A viscous oil obtained by: polymerizing, at a temperature above 600F. and below 750 F., a normal, alpha mono-olefin having from 5 to 18carbon atoms with a mixture of elemental phosphorus and elementalsulfur, the quantity of said phosphorus and sulfur being greater thanabout 0.01 per cent and less than one per cent by weight of the combinedweight of said olefin and said mixture.

13. A viscous oil obtained by: polymerizing, at about 650 F. for about10 hours, octene-l in the presence of about 0.3 per cent of phosphoruspentasulfide.

14. A viscmls oil obtained by: polymerizing, at about 700' I". for about3 hours, decene-l in the presence of about 0.3 per cent of phosphoruspentasulfide.

15. A viscous oil obtained by: polymerizing, at about 615 F. for about10 hours, decene-l in the presence of about 0.2 per cent of phosphorusand about 0.7 per cent of sulfur.

WILLIAM E. GAR-WOOD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date Loane et al. Apr. 6, 1M3 Kelso et al.Apr. 6, 1943 Hughes et al Aug. 14, 1945 Sparks et al. Jan. 25, 1949Number Certificate of Correction Patent N 0. 2,500,163 March 14:, 1950WILLIAM E. GARWOOD It is hereby certified that error appears in theprinted specification of the above numbered patent requiring correctionas follows:

Column 4, line 58, for GO-08 F. read 6080 F.; columns 5 and 6, Table I,Run N o. 4, line 24, for 20 read 20; same table, in the portionbeginning with Run N o. 7, second line under Olefin, for Per Cent byWeight read Molar Proportion; tenth line under Residual Oil, forPhosphorus read Per Gent Phosphorus; same line, Run No. 8, for 90.002read 0.002; column 9, line 13, for poor read pour; and that the saidLetters Patent should be read as corrected above, so that the same mayconform to the record of the case in the Patent Oflice.

Signed and sealed this 26th day of December, A; D. 1950.

THOMAS F. MURPHY,

1. THE METHOD OF PREPARATION OF A VISCOUS OIL, WHICH COMPRISES:POLYMERIZING, AT A TEMPERATURE ABOVE 600*F. AND BELOW 750*F., A NORMAL,ALPHA MONO-OLEFIN HAVING FROM 5 TO 18 CARBON ATOMS WITH A MATERIALSELECTED FROM THE GROUP CONSISTING OF A PHOSPHORUS SULFIDE, ELEMENTALPHOSPHORUS WITH ELEMENTAL SULFUR, AND MIXTURES THEREOF, THE QUANTITY OFSAID MATERIAL BEING LESS THAN ONE PER CENT BY WEIGHT OF THE COMBINEDWEIGHT OF SAID OLEFIN AND SAID MATERIAL.